JPH11218654A - Optical fiber cable, and its manufacturing method and laying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-core optical fiber cable whose skew (transmission delay time difference) is made as small as possible. SOLUTION: The optical fiber cable is constituted by arranging around a center body 18 optical fiber units 15 each having ribbons of coated optical fibers 13 formed by arraying and uniting coated optical fibers 11 in parallel so that the coated optical fibers 11 draw spiral tracks along the length while the same pitch, the same direction, the same spiral radius, and different center axes. In this case, the coated optical fiber 11 of the optical fiber units 15 are all equalized in physical length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable in which a difference in optical transmission delay time between optical fibers is reduced.

[0002]

2. Description of the Related Art An optical fiber cable used for optical parallel transmission between optical transmission devices has a multi-core structure and a small skew (difference in optical transmission delay between optical fibers) from the viewpoint of mass transmission of information. Is required. Since this skew is determined by the difference in physical length and the difference in refractive index of the optical fiber core, it is required to reduce them as much as possible.

On the other hand, conventionally, a multi-core optical fiber cable having a cross section shown in FIG. 8 or 9 has been manufactured and used. FIG. 8A is a cross-sectional view of an example of an optical fiber cable according to the related art, and FIG. 8B is a cross-sectional view of a tape-shaped core used in the optical fiber cable of FIG. 8A. FIG. 9A is a cross-sectional view showing another example of the optical fiber cable according to the prior art.
FIG. 10B is a perspective view of an optical fiber unit used for the optical fiber cable of FIG. 9A.

In FIG. 8, numeral 32 denotes a plurality of spiral grooves 32a in the longitudinal direction around a strength member 36 made of steel wire or the like.
A long container 33 made of a plastic such as polyethylene, formed with a plurality of optical fiber core wires 33a in which glass fibers are coated with an ultraviolet curable resin or the like are arranged in parallel, and a collective coating 33b is provided. A plurality of tape-shaped cords are stacked and accommodated in the groove 32a of the long container 32. Reference numeral 34 denotes an upper winding, and reference numeral 35 denotes an outer coating made of polyethylene or the like.

In FIG. 9, the optical fiber unit 3
Reference numeral 8 denotes a plurality of tape-like core wires 33 shown in FIG. 8B which are stacked and accommodated in a groove of a long container 37 made of plastic having one spiral groove in the longitudinal direction. A plurality of the optical fiber units 38 are twisted around a central body in which a coating 40 made of plastic or the like is provided around a strength member 39 made of a steel stranded wire or the like. The outer side is provided with an upper winding 41 and an outer coating 42 made of plastic or the like.

However, in the conventional optical fiber cable shown in FIG. 8 or FIG. 9, each of the optical fiber cores in a tape-shaped core obtained by integrating a plurality of optical fiber cores in parallel is a tape-shaped core. At the stage when the wires are formed, the optical fiber cores in them are arranged in parallel, so that the physical lengths of the optical fiber cores in one tape-shaped core are all the same. After being formed as a fiber cable, the trajectory drawn by each optical fiber core within the tape-shaped core in the longitudinal direction of the optical fiber cable is different, and the physical length is slightly different from each other.

For example, focusing on one tape-shaped core in the optical fiber cable of FIG. 8A, consider the trajectory of the optical fiber in the core. Since the optical fiber cores are arranged in parallel in one plane within the tape-shaped core, depending on the position of the optical fiber core within the tape-shaped core, from the central axis of the optical fiber cable to the optical fiber core. Distances are slightly different. Further, since the tape-shaped core wire is accommodated in the spiral groove, the optical fiber core wire therein also draws a spiral locus around the central axis, so that the spiral radius differs.

Therefore, even in the case of an optical fiber core included in one tape-shaped core in the longitudinal direction of the optical fiber cable, it has a different helical radius, and strictly speaking, the physical length of the optical fiber core is Will be different. When the tape-shaped core is manufactured, the optical fibers in one tape-shaped core are all of the same physical length, so the optical fiber in the process of being cabled is stretched or stretched due to elongation strain. Such a phenomenon occurs because the physical length of each optical fiber core changes due to contraction or the like under a compressive strain caused by a force.

[0009]

As described above, in a multi-core optical fiber cable manufactured according to the prior art, the physical length of each optical fiber core in a tape-shaped core used therein is: At the stage of becoming an optical fiber cable, it is not necessarily the same. Therefore, the skew of the conventional optical fiber cable may be 1.0 Psec / m or more, so that an optical fiber cable having a smaller skew is required. An object of the present invention is to provide an optical fiber cable having a skew as small as possible, a method of manufacturing the same, and a method of laying the same.

[0010]

SUMMARY OF THE INVENTION An optical fiber cable according to the present invention comprises a plurality of optical fiber units having a plurality of tape-shaped optical fibers in which a plurality of optical fiber cores are arranged in parallel and integrated. Wherein the optical fiber cores are arranged in a longitudinal direction around the body so as to draw a trajectory of a spiral state having the same pitch, the same direction, the same helical radius and different central axes, and The physical lengths of the lines are the same.

As the optical fiber unit, a plurality of tape-shaped optical fibers having a plurality of optical fiber cores arranged in parallel and provided with a collective coating on the outside are laminated from a plastic having a groove in the longitudinal direction. A plurality of optical fiber ribbons, each of which is accommodated in the groove of a long storage body, and in which a plurality of optical fiber ribbons are arranged in parallel and provided collectively on the outside, are laminated, and a plurality of tape-shaped ribbons are formed of plastic. Some are housed in the holes of a lengthy tube.

In order to manufacture such an optical fiber cable, an optical fiber having a laminated body in which a plurality of optical fiber cores are arranged in parallel and a plurality of integrated tape-shaped cores are linearly stacked. It can be manufactured by supplying a plurality of units and twisting the optical fiber units around the central body in the longitudinal direction and twisting them at 360 ° / pitch in synchronization with the twisting pitch.

In addition, a plurality of optical fiber units each having a laminated body in which a plurality of optical fiber cores are arranged in parallel and integrated with a plurality of tape-shaped cores are supplied, and a plurality of optical fiber units are provided around the central body. The optical fiber cable is formed by twisting so that the position of the optical fiber core in the direction does not change the radius from the central body, and the optical fiber cable is rotated at the same cycle as the twisting cycle in the direction in which the twist returns. By laying the cable, the skew of the optical fiber cable after the laying is reduced even if the cable has a large skew at the time of manufacturing the cable, as in the case of the conventional optical fiber cable. Can be smaller.

[0014]

FIG. 1A is a cross-sectional view of an embodiment of an optical fiber cable according to the present invention, and FIG. 1B is a cross-sectional view of an optical fiber unit used therein.
(C) is a cross-sectional view of the tape-shaped cord. In the figure, reference numeral 11 denotes an optical fiber core provided by coating a glass fiber with an ultraviolet curable resin or the like, 12 denotes a collective coating made of an ultraviolet curable resin or the like, and 13 denotes a plurality of optical fiber cores 11 arranged in parallel. It is a tape-shaped core wire integrated by the collective coating 12.

Reference numeral 14 denotes a long container made of plastic or the like and provided with a single linear groove 14a. Reference numeral 15 denotes a plurality of tape-shaped cores 13 stacked in the groove 14a of the long container 14. The optical fiber unit accommodated therein, 16 is a tensile strength member made of steel wire, steel stranded wire, FRP, etc., 17 is a coating made of plastic such as polyethylene, 18 is a central body formed by coating the tensile strength member 16 with a coating, 19 is a plastic tape or the like. The outer winding 20 is made of polyethylene or the like.

Although FIG. 1 shows an example in which the number of optical fiber cores 11 of the tape-shaped core 13 is twelve, any number may be used as long as the number is plural. Further, although six optical fiber units 15 are shown in the figure, any number may be used. Further, an example in which the coating 17 is provided around the tensile member 16 as the central body 18 is illustrated, but an aggregate of optical units may be used as long as the central body has a substantially circular cross section. Also, the cable may be used for other purposes. It is also possible to use only some of the optical fiber units 15 twisted around the center body 18 as the optical fiber unit 15 according to the present invention, and to fill the other with an ordinary optical fiber cable unit or the like. is there.

In the optical fiber cable according to the present invention, the optical fiber unit 15 is helically twisted around the center body 18, and the helical state is determined in the longitudinal direction by each of the optical fibers in the optical fiber unit 15. 11 are twisted so as to draw spiral tracks having the same pitch, the same direction, the same spiral radius, and different central axes. That is, as shown in FIG. 1 (A), if one optical fiber unit 15 is focused on and a groove 14a of the optical fiber unit is directed upward, as shown in FIG. Even if it is seen, the groove 14a of the same optical fiber unit 15 is always twisted so as to face upward.

FIG. 2 is a view for explaining a spiral state according to the present invention. The upper figure is a side view, the lower figure is an X section, a Y section,
It is a cross section in the Z section. In FIG. 2, the central body 18
The figure shows a case where six optical fiber units according to the present invention are twisted around. Each of the six optical fiber units is tentatively numbered from 1 to 6, 1 has a linear groove, 2 has linear streaks at two places above and below the surface, and 3 has a surface. A linear streak at three equally divided parts, a linear streak at four equally divided parts on the surface, a linear streak at one single part on the surfaces 5, 6 Then, one of the grooves or streaks of each optical fiber unit is aligned and twisted so as to be on a certain cross section, for example, an X cross section.

Then, another section, for example, a Y section or a Z section
Even if the section is cut at an arbitrary point in the longitudinal direction such as the section and the section is viewed, the positions of 1 to 6 are always rotating around the central body, but the positions of the grooves or streaks are exactly the same as the X section and simply translate. That is, the spiral state according to the present invention is in the spiral state.

By twisting the optical fiber units so as to obtain such a spiral state, the tape-shaped core wires included in the optical fiber unit and all the optical fiber cores in the tape-shaped core wire have the same pitch and the same pitch. Since the trajectory is drawn in a helical state having different central axes with the same helical radius in the same direction, the physical length of each optical fiber is theoretically exactly the same. Therefore, such an optical fiber cable is suitable for large-capacity parallel optical transmission since the skew of each optical fiber core becomes small.

In the example shown in FIG. 1, an optical fiber cable using a tape-shaped core wire accommodated in a long container having a linear groove as an optical fiber unit is shown. As an optical fiber unit used for a cable, there is another embodiment having a cross-sectional view shown in FIG. In the example of FIG. 3, a plurality of tape-shaped core wires 13 are laminated to form a hole 2 of a long tube 21 made of plastic.
The optical fiber unit 22 is housed in the optical fiber unit 1a. It is desirable that the gap in the hole 21a is filled with a filler so that the tape-shaped core 13 does not move in the hole 21a.

Each of the optical fibers in the optical fiber unit is twisted in the longitudinal direction so as to draw a spiral trajectory having the same pitch, the same direction, the same helical radius, and different center axes. To match, you can do as follows. FIG. 4 is a view for explaining the twisting method, that is, the twisting method with twisting. First,
A plurality of optical fiber units shown in FIG. 1B are formed and wound around reels with the grooves facing outward.
As shown in FIG. 4, the reels 23 are attached to the rotating cages 24, respectively, and the rotating cages 24 are rotated with respect to the ground 25 so that the optical fiber units wound on the reels 23 are oriented in the direction of the axis 26 perpendicular to the plane of the drawing. For example, it is pulled upward with respect to the paper. At that time, the shaft is simultaneously pulled out through the central body.

Then, since each optical fiber unit is drawn out while rotating around the central body, it is twisted around the central body. In addition, rotating cage 2
Even if 4 rotates, the axis of each reel 23 is always oriented in a fixed direction with respect to the ground (in the figure, always parallel to the ground). By making the axial direction of the reel 23 constant with respect to the ground 24, the optical fiber unit itself is not twisted around its own axis, but if the optical fiber unit is viewed from the central body,
As the fiber optic unit rotates around the central body, it appears that the fiber optic unit itself is rotating counterclockwise around its own axis with the same period.

The optical fiber unit makes one round around the center body during the length of one pitch of the twisting of the optical fiber unit, but the optical fiber unit itself rotates 360 degrees around its axis when viewed from the center body. ° Appears to rotate. Such a twisting method is called twisting.

As described above, when the optical fiber unit is twisted around the center body with a twist, the optical fiber unit itself does not rotate around its own axis when viewed from the ground. Each section of the cross-section will draw a spiral trajectory in the longitudinal direction of the fiber optic cable in the same direction with the same helical radius while simply changing position in a helical fashion about the central body.

The fact that the trajectories drawn by the portions of the cross section of the optical fiber unit are in the same spiral radius and spiral state in the same direction means that the optical fiber unit has a linear groove having a linear groove as shown in FIG. As long as the tape-shaped cores are stacked and stored in the length storage unit, each optical fiber core of the tape-shaped core draws the same spiral radius and the spiral state in the same direction around different central axes. Will be. The same applies to the case of the optical fiber unit shown in FIG.

As described above, as the optical fiber cable, the trajectory drawn by each optical fiber core wire in the longitudinal direction has the same helical radius and helical state in the same direction, so that the physical length of each optical fiber core is the same. An example of an optical fiber cable for reducing the skew has been described.However, even if the skew of the optical fiber cable is not reduced, the skew after the laying can be reduced by manufacturing the optical fiber cable by a specific method and laying the optical fiber cable by a specific method. It is also possible to make it smaller. Hereinafter, the method will be described.

First, an optical fiber cable laid by this specific method is manufactured by a specific method as follows. An optical fiber unit having the cross section shown in FIG. 2B or FIG. 3 is prepared. Figure 1 up to this point
This is the same as the optical fiber cable of (A), but the twisting is performed by a method as shown in FIGS. FIG. 5 is FIG.
FIG. 6 is a perspective view of an optical fiber cable when the optical fiber unit of (B) is used, and FIG. 6 is a diagram illustrating a twisting method in that case, that is, a twisting method without twisting.

In the optical fiber cable shown in FIG.
The optical fiber cable 26 is formed by twisting the optical fiber unit 15 around the cable 8 such that the groove 14a of the optical fiber unit 15 always faces the outside of the cable. Reference numeral 19 denotes a coarse winding made of a plastic tape or the like, and no upper winding or external coating is provided.

The twisting is performed as shown in FIG.
4 is mounted by attaching a reel 23 around which the optical fiber unit is wound so that the groove is on the outside. 6, in the same manner as in FIG. 4, the optical fiber units are respectively pulled out from the reels 23 in a direction perpendicular to the plane of the paper and above the plane of the paper, and twisted around the central body drawn through the axis 26. .

Also, in the case of FIG. 6, unlike the case of FIG. 4, the axis of the reel 23 always faces the rotating circumferential direction of the rotating cage 24. This twisting method is a method called no twisting. In this manner, in the optical fiber unit unreeled from the reel 23, the groove is always directed in the direction opposite to the central body, and when the optical fiber cable is formed, all the grooves of each optical fiber unit face the outside. It is suitable. In addition, 25 shows the earth.

With this optical fiber cable 26 as it is, each optical fiber core of an arbitrary tape-shaped core included in the optical fiber unit is divided into a central portion and a peripheral portion of the tape-shaped core. Since the distance from the central axis of the optical fiber cable is different, the optical fiber core wire has a different helical radius of the spiral locus drawn around the central body, and the optical fiber core wire of a certain length of the optical fiber cable has a different length. The physical length will be strictly different. Therefore, the skew of this optical fiber cable does not decrease as it is.

Therefore, the optical fiber cable 26 is laid by the following method. FIG. 7 (A) is a perspective view showing the method of laying, and FIG. 7 (B) is a perspective view of the optical fiber cable after laying. The drum 27 around which the optical fiber cable 26 is wound is attached to a cage 30 in which the direction of the drum axis rotates, and the cage 30 is placed on the rotating roller 31 so that the drum axis is moved in a plane perpendicular to the direction in which the optical fiber cable 26 is extended. The optical fiber cable 26 is paid out while rotating. 32 is a guide die,
The optical fiber cable is guided in a straight line.

The direction of rotation of the cage 30 at this time is a direction in which the twisting of the optical fiber unit of the optical fiber cable returns, and the rotation cycle is synchronized with the twisting cycle of the optical fiber unit. Then, the twisting of the unwound optical fiber unit of the optical fiber cable is completely returned, and each optical fiber unit becomes a straight line parallel to the central body 18. Since the optical fiber unit was originally twisted around the center body, the optical fiber unit is slightly longer than the center body by the length corresponding to the twist rate of twisting. There is no particular problem since the optical fiber unit is almost linear when the unit is slightly meandered.

The optical fiber cable 28 after installation is shown in FIG.
As shown in (B), since the optical fiber units 15 are arranged in parallel around the central body 18, the tape-shaped cores included in each optical fiber unit 15 or each of the tape-shaped cores included in the tape-shaped cores are included. The optical fiber cores are all in a parallel state, that is, a linear state. Accordingly, the physical lengths of the optical fiber cores are all the same, and the skew of the optical fiber cable 28 after installation can be reduced.

[0036]

Embodiment 1 As Embodiment 1, an optical fiber cable having the structure shown in FIG.
Skew of two tape-shaped cores and skew (transmission delay) of tape-shaped cores of an optical fiber cable in which four tape-shaped cores are stacked to form an optical fiber unit, and six optical fiber units are twisted. Time difference) was measured. In addition,
Here, the skew is obtained by measuring the transmission delay time of another optical fiber core with reference to the transmission delay time of the first optical fiber core for 12 optical fiber cores in one tape-shaped core. It is graphed and obtained as the difference between the maximum delay time and the minimum delay time.

As a result, FIG. 10A shows the skew in the tape-shaped core before the optical fiber unit is formed.
(B) shows the skew of the tape-shaped core after the optical fiber cable. The former is 0.52 Psec / m, the latter is 0.50 Psec / m, and there is almost no change.
It can be seen that it is less than sec / m.

As a comparative example 1, a conventional optical fiber cable having a structure shown in FIG. 8 was manufactured using 12 tape-shaped cords. The resulting skew is as shown in FIG. 11, in which FIG. 11 (A) shows the skew of the tape-shaped core before cable conversion, and FIG. 11 (B) shows the tape-shaped core after forming an optical fiber cable. Shows the skew of It can be seen that the skew, which was 0.48 Psec / m before the cable, was increased to 1.01 Psec / m after the cable.

Accordingly, comparing Example 1 with Comparative Example 1, it can be seen that the skew of the optical fiber cable according to the present invention is smaller than that of the conventional optical fiber cable.

Next, two optical fiber cables having the structure shown in FIG. 5 were manufactured using 12 cores of tape. Then, the skew of the optical fiber cable was measured, and one of the optical fiber cables was laid according to the laying method of the present invention shown in FIG. As No. 2, laying was performed such that the cable was normally extended from the drum without rotating the drum shaft in a plane perpendicular to the feeding direction. FIG. 12 is a diagram showing a change state of the skew in the case of the laying method of the present invention. FIG.
(B) shows the skew after the installation. 1.12P before installation
sec / m, which is not a very good value, but after installation.
It can be seen that the skew is improved to 48 Psec / m.

FIG. 13 is a diagram showing a change state of the skew when the laying is performed according to the normal method of Comparative Example 2.
FIG. 13A shows the skew before installation, and FIG. 13B shows the skew after installation. In this case, the skew before installation is 1.12 Psec / m, and the skew after installation is 1.13 Psec / m.
At Psec / m, it can be seen that there is no change due to the installation and the level is not good.

[0042]

According to the optical fiber cable of the present invention, the optical fiber unit having a plurality of tape-shaped optical fibers is formed such that the optical fiber optical fibers included in the optical fiber unit have the same pitch in the longitudinal direction around the center body. Since the optical fibers are arranged so as to draw spiral tracks having different central axes in the same direction and the same spiral radius, optical fibers having the same physical length and small skew can be obtained.

As an optical fiber unit, a plurality of tape-shaped cores are stacked and accommodated in a long container made of plastic having a linear groove in the longitudinal direction, or a tape-shaped core. When a plurality of laminated layers are used and accommodated in the hole of a long tube made of plastic, the skew of each tape-shaped core in the optical fiber unit at the time of manufacturing the optical fiber unit is small,
Also, the skew at the time of forming a multi-core optical fiber cable can be reduced.

Further, in order to manufacture the optical fiber cable of the present invention, an optical fiber unit having a laminated body in which a plurality of tape-shaped core wires are linearly laminated is supplied, and the optical fiber unit is provided around the central body in the longitudinal direction. By twisting the optical fiber units while applying a twist of 360 ° / pitch in synchronization with the twisting pitch, it is possible to manufacture an optical fiber cable with a small skew using a conventionally used manufacturing apparatus. .

Further, an optical fiber unit having a laminated body in which a plurality of tape-shaped core wires are linearly laminated is supplied,
An optical fiber cable is formed by twisting the optical fiber units without so-called twisting so that the respective positions of the optical fiber core wires in the longitudinal direction around the central body rotate without changing the radius from the central body. And
The skew of the optical fiber cable after installation can also be reduced by laying the optical fiber cable while rotating the optical fiber cable in the direction in which the twist of the optical fiber unit returns, at the same cycle as the twisting cycle.

[Brief description of the drawings]

1A is a cross-sectional view of an embodiment of an optical fiber cable according to the present invention, FIG. 1B is a cross-sectional view of an optical fiber unit used in the embodiment, and FIG. FIG.

FIG. 2 is a view for explaining a spiral state according to the present invention, in which an upper figure is a side view, and a lower figure is a transverse sectional view in an X section, a Y section, and a Z section.

FIG. 3 is a cross-sectional view of another embodiment of the optical fiber unit used for the optical fiber cable of the present invention.

FIG. 4 is a diagram illustrating a twisting method with a twist.

FIG. 5 is a perspective view of an optical fiber cable in which optical fiber units are twisted without being twisted.

FIG. 6 is a diagram illustrating a twisting method without twisting.

FIG. 7A is a perspective view showing an embodiment of a laying method according to the present invention, and FIG. 7B is a perspective view showing an optical fiber cable after laying.

FIG. 8A is a cross-sectional view showing an example of an optical fiber cable according to the related art, and FIG. 8B is a cross-sectional view of a tape-shaped core used in the optical fiber cable.

FIG. 9A is a cross-sectional view showing another example of an optical fiber cable according to the related art, and FIG. 9B is a perspective view of an optical fiber unit used therein.

10A and 10B are diagrams showing a change in skew of a tape-shaped core wire before and after the optical fiber cable of the present invention shown in FIG. 1A is formed into a cable, wherein FIG. The value after cable conversion is shown.

11A and 11B are diagrams showing a change in skew of a tape-shaped core wire before and after the optical fiber cable according to the conventional technique shown in FIG. 8A, and FIG.
Indicates the value after conversion into a cable.

12A and 12B are diagrams illustrating a change in skew before and after installation when the optical fiber cable of FIG. 5 is installed by the installation method according to the present invention, wherein FIG. )
Indicates the value after installation.

13A and 13B are diagrams showing a change in skew before and after installation when the optical fiber cable of FIG. 5 is installed by a normal installation method, where FIG. 13A shows a value before installation and FIG. The value after installation is shown.

[Explanation of symbols]

 11: Optical fiber core wire 12: Collective coating 13: Tape-shaped core wire 14: Long storage body 14a: Groove 15, 22: Optical fiber unit 16: Tensile member 17: Coating 18: Central body 19: Upper winding 20: External Coating 21: Long tube 21a: Hole 23: Reel 24: Rotating cage 25: Ground 26, 28: Optical fiber cable 27: Drum 29: Coarse winding 30: Cage 31: Rotating roller 32: Guide die

Claims (5)

[Claims] An optical fiber unit having a plurality of tape-shaped optical fibers in which a plurality of optical fiber optical fibers are arranged in parallel and integrated with each other, the optical fibers in said optical fiber unit being longitudinally disposed around a central body. An optical fiber cable, wherein the core wires are all arranged so as to draw a spiral trajectory having the same pitch, the same direction, the same helical radius, and different central axes. 2. The optical fiber unit according to claim 1, wherein the optical fiber unit includes a plurality of tape-shaped optical fibers each having a plurality of optical fiber cores arranged in parallel and provided with a collective coating on the outside, and a plurality of tape-shaped cores laminated in a longitudinal direction. The optical fiber cable according to claim 1, wherein the optical fiber cable is housed in the groove of a long storage body made of plastic having: 3. The optical fiber unit according to claim 1, wherein a plurality of optical fiber cores are arranged in parallel, and a plurality of tape-shaped optical cores provided with a collective coating on the outside are laminated to form a long tube made of plastic. The optical fiber cable according to claim 1, wherein the optical fiber cable is housed in the hole. 4. An optical fiber unit having a multilayer body in which a plurality of optical fiber cores are arranged in parallel and a plurality of integrated tape-shaped cores are linearly stacked and supplied, and the optical fiber unit is provided around a central body. A method for manufacturing an optical fiber cable, comprising twisting the optical fiber units in the longitudinal direction while twisting them at 360 ° / pitch in synchronization with the twisting pitch. 5. An optical fiber unit having a laminated body in which a plurality of optical fiber cores are arranged in parallel and a plurality of integrated tape-shaped cores are linearly stacked and supplied, and the optical fiber unit is provided around a central body. The optical fiber unit is twisted to form an optical fiber cable so that each position of the optical fiber core in the longitudinal direction does not change the radius from the central body, and the optical fiber cable is twisted to the optical fiber unit. Wherein the fiber is laid while being rotated at the same cycle as the twisting cycle in the direction in which the optical fiber returns.